| 摘要 |
PURPOSE:To cope with a DC input voltage varied in a wide range by one DC power supply device by fractionizing the variance range of the DC input voltage and cascading constant voltage circuits which have fractionized ranges as operating ranges. CONSTITUTION:Constant voltage circuits 12, 15, and 17 are cascaded to a DC constant voltage circuit. Since the base voltage of a transistor TR 12-2 of the circuit 12 is set to about 36V certain voltage by a Zener diode 12-1 in this constitution, the voltage between the base and the collector is changed in accor dance with application of the DC input voltage and the voltage at a point (a) becomes about 34V if 57-36V DC input voltage is applied to the collector. If the DC input voltage is, for example, 30V, the output of a comparing circuit 13-1 to which 36V certain voltage is applied becomes positive, and therefore, a current is flowed to a relay 11-1 through a diode 13-2 to short-circuit a contact rl, and the voltage at the point (a) becomes 30V. The circuit 15 converts the DC input voltage to about 20V output voltage and outputs it, and the circuit 17 converts the DC input voltage to constant 12V output voltage and outputs it. Thus, 57-14V DC voltage is outputted as constant 12V voltage. |
